We have been studying progesterone metabolism in the development, function and aging of the gonad in C. elegans. When we analyzed the pattern of progesterone metabolism in aging animals, we found that it is markedly reduced in aging animals. The reduction of metabolites initially was thought to be related to steroid enzymes, but in further studies we found that these alterations are related to the P-450 enzymes in C. elegans. The P-450 enzymes in C. elegans are inducible as in rats and mice by chemicals such as Aroclor 1254 or drugs such as phenobarbitol. We have begun to study the role of these enzymes in the metabolism and detoxification of chemicals and how might these enzymes play a role in the aging of the animal. .